The Flow Cytometry and Cell Sorting Core will provide standard technology and analysis services to the Philadelphia ACE investigators. This core will be used by both research projects, both clinical components and the pilot research project. It is non-duplicative of other services or facilities available to ACE investigators. The Core will be built around a state-of-the-art sorting system that has fixed alignment of the three laser beams (for the blue, red, and UV lasers), which can perform multi-color analysis (up to 13) in a single cell and simultaneously sort 4 subpopulations with high purity, high recovery, high speed, and sterile cell sorting, thus being essential for the experiments proposed in projects by the Pis. The core resources are not otherwise available at the Thomas Jefferson University or through other grant mechanisms. Two certified specialists, including the Core Director and one full-time research assistant, will routinely run this core to provide high-quality service. The goals of the Flow Cytometry and Cell Sorting Core are to: 1) Offer high quality and affordably priced services for analysis and sorting of a range of cell types, with particular emphasis on immune cells according to the needs of autoimmunity investigators in the ACE; 2) Consult with ACE members to determine their individual analytical cytometry needs, to aid in the development of appropriate protocols and techniques, giving advice for both standard and specialized services; 3) Promote interaction and collaboration among investigators by providing a centralized facility where exchange of results and ideas will be facilitated. As flow cytometry will be extensively used by all the Pis, this well-equipped core, in both machine and personnel, will provide a powerful tool for the overall success of this ACE.